JP4912955B2 - Aerodynamic noise reduction device, fluid equipment, moving body and rotating equipment - Google Patents

Description

  The present invention relates to an aerodynamic noise reduction device, a fluid device, a moving body, and a rotating device that generate an air flow by the action of discharge plasma and control the flow of fluid to reduce noise.

  Aerodynamic noise caused by the flow of air has become a major technical issue in fluid equipment, such as the sound of jets at the outlet of plants, the sound of blowers and turbines, and the sound of home air conditioners. In addition, with the speeding up of automobiles and Shinkansen, aerodynamic noise has become an important solution for vehicles. This is because such aerodynamic noise has a feature that it suddenly increases as the airflow velocity or the moving velocity increases. For this reason, in recent years, researches have been actively conducted to grasp the generation mechanism of aerodynamic noise and reduce the generation of aerodynamic noise by controlling the flow (for example, see Non-Patent Document 1).

  As a conventional aerodynamic noise reduction method, for example, a method of providing a triangular pyramid-shaped turbulent flow promoter in the vicinity of the blowout outlet, an ultrasonic vibrator or an electric heater in the vicinity of the blowout outlet, etc. A technique for making the thickness of the boundary layer in the circumferential direction of the blowout port non-uniform by partially changing the boundary layer of the blowout port to turbulent flow is disclosed (for example, Patent Document 1). 2). Accordingly, aerodynamic noise at the outlet is reduced by weakening the synchronicity in the circumferential direction in the boundary layer, or by reducing the strength of the shear flow by increasing the thickness of the boundary layer at the outlet. Moreover, the technique which makes a blower outlet corrugated aiming at the same effect is also disclosed (for example, refer patent document 3). These technologies are based on the aerodynamic noise generation mechanism in which the noise generated by the blowout jet depends on the strength of the shear flow around the jet and generates a very large aerodynamic noise when the shear flow is circumferentially synchronized. It is a thing.

In addition, as a method for reducing the rotational noise and stationary blade interference generated by an axial fan or turbine, the gas supplied to the inside of the stationary blade by a blower for generating a jet flow is ejected from the trailing edge of the stationary blade, Research has been conducted on a method for reducing static blade interference sound generated by interference between a stationary blade wake and a moving blade by reducing the velocity deficit of the blade trailing flow (see, for example, Non-Patent Document 2). .
Journal of the Japan Society of Fluid Mechanics, Nagare 20 (2001), pp251-pp230 Japanese Patent No. 3139588 Japanese Patent No. 2641186 Japanese Patent No. 3383798 AIAA Journal, Vol.39, No.3, March 2001, pp.458-pp.464

  However, in the conventional method for reducing aerodynamic noise at the outlet, the turbulence promoting body that partially transitions the boundary layer of the outlet to turbulent flow is provided. There was a problem of becoming. Further, since the shape of the turbulent flow promoting body is formed in a predetermined shape, there is a problem that aerodynamic noise can be reduced only under a certain range of wind speed conditions in which the shape exhibits an effect. Furthermore, there are problems on the apparatus that a large ultrasonic vibrator, electric heater, etc. must be provided for the flow field, and there is a problem that fine control is not effective in the apparatus configuration.

  Further, in the conventional method for reducing the rotational noise generated by the axial fan or turbine and the stationary blade interference noise, there remains a problem with application to an actual machine, for example, a blower for generating a jet is required separately.

  Here, the inventors have proposed an airflow generation device that generates an airflow by the action of discharge plasma and controls the flow of the fluid by the generated airflow. And the inventors considered reducing aerodynamic noise using this airflow generator. The velocity of the flow induced by the airflow generator can be from several m / s to several tens m / s. Further, with this airflow generation device, it is possible to generate a very thin layered flow while appropriately controlling it.

  Moreover, since the airflow generation device can be formed in a thin plate shape, for example, it can be arranged on a curved surface or the like. It is also easy to arrange a plurality of airflow generation devices. Furthermore, by controlling the applied voltage, it is possible to appropriately control the speed of the induced air flow and the period for generating the air flow.

  Therefore, the present invention has been made to solve the above-described problems, and corresponds to various aerodynamic noise generation mechanisms, and can reduce aerodynamic noise under a wide range of conditions. An object is to provide a device, a moving body, and a rotating device.

In order to achieve the above object, an aerodynamic noise reduction device according to the present invention includes a first electrode, a second electrode spaced apart from the first electrode, the first electrode, and the first electrode. A voltage applying mechanism capable of applying an alternating voltage between the first electrode and the second electrode, generating an air flow by discharge between the first electrode and the second electrode, and generating the air flow as an aerodynamic noise source The aerodynamic noise is reduced by acting on at least a part of the main flow.

According to this aerodynamic noise reduction device, an airflow can be generated by applying an alternating voltage between the first electrode and the second electrode, and this airflow can be generated in a mainstream that is a source of aerodynamic noise. Aerodynamic noise can be reduced by acting on at least a part of the flow.

  Moreover, the above-described aerodynamic noise reduction device can be provided at a predetermined position such as a fluid device, a moving body, or a rotating device. As a result, aerodynamic noise generated from these devices can be reduced.

  According to the aerodynamic noise reduction device, the fluid device, the moving body, and the rotating device of the present invention, it is possible to reduce aerodynamic noise under a wide range of conditions in response to various aerodynamic noise generation mechanisms.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view schematically showing an aerodynamic noise reduction device 10 according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the state of speed change of the induced flow 25.

  As shown in FIG. 1, the aerodynamic noise reduction device 10 has the same electrode 21 as a first electrode embedded in a dielectric 20, the same distance from the surface of the electrode 21 and the dielectric 20, and dielectric A discharge power source that applies a voltage between the electrode 22, which is spaced apart from the surface of the body 20 in the horizontal direction and is embedded in the dielectric 20, and the electrodes 21 and 22 via the cable 23. 24.

  The dielectric 20 is made of a known solid dielectric material. Specific examples of the material constituting the dielectric 20 include, but are not limited to, electrical insulating materials such as inorganic insulators such as alumina and glass, and organic insulators such as polyimide, glass epoxy, and rubber. Instead, it is appropriately selected from known solid dielectric materials in an environment where the airflow generator is used.

  Moreover, as the electrodes 21 and 22, a general copper plate or the like is used. By using a copper plate or the like as the electrodes 21 and 22, the thickness of the electrodes 21 and 22 can be reduced, and the thickness of the aerodynamic noise reduction device 10 itself can be easily configured to be several hundred μm or less. .

  The discharge power supply 24 functions as a voltage application mechanism and applies a voltage between the electrodes 21 and 22. From the discharge power supply 24, for example, a pulsed output voltage that intermittently outputs positive and / or negative voltage, an alternating voltage that alternately outputs positive and negative pulsed voltage, and alternating current An output voltage or the like having a waveform of (sine wave, intermittent sine wave) is output. Further, the discharge power supply 24 may apply a voltage between the electrodes 21 and 22 while adjusting the voltage value, for example, by adjusting the output voltage and outputting the output voltage. Specifically, for example, when positive and negative voltages are alternately and intermittently output at a predetermined duty ratio, two pulses are set to a high output from the beginning, and the subsequent two pulses are set to a half of the output. For example, control of repeatedly applying a combination of two high-power pulses and half of the two power pulses. Note that the present invention is not limited to this, and the voltage control can be set as appropriate according to the use conditions and the application.

  Next, a phenomenon in which the induced flow 25 is generated by the aerodynamic noise reduction device 10 will be described.

  When a voltage is applied between the electrode 21 and the electrode 22 from the discharge power supply 24 and a potential difference equals or exceeds a certain threshold value, a discharge is induced between the electrode 21 and the electrode 22. In the aerodynamic noise reduction device 10, since the dielectric 20 is interposed between the electrode 21 and the electrode 22, it can be stably maintained without being subjected to arc discharge even under a high temperature or dusty environment. Barrier discharge occurs and low temperature plasma is generated. In these discharges, energy can be given only to the electrons in the gas, so that the gas can be ionized to generate electrons and ions with little heating of the gas. The generated electrons and ions are driven by an electric field, and momentum shifts to gas molecules when they collide with gas molecules. That is, the induced current 25 can be generated near the electrodes by applying a voltage between the electrodes. The magnitude and direction of the induced current 25 can be controlled by changing the current-voltage characteristics such as the voltage, frequency, current waveform, and duty ratio applied to the electrodes.

  In the barrier discharge under atmospheric pressure as described above, when a DC voltage is applied between the electrodes 21 and 22, charges accumulate on the surface of the dielectric 20 as the discharge progresses, and the electric field between the electrodes 21 and 22 is relaxed. Eventually, the electric field cannot maintain the ionization of the space, and the discharge stops. In order to prevent the discharge from being stopped, it is necessary to remove the electric charge stored on the surface of the dielectric 20, and for this purpose, a pulsed positive / negative bipolar voltage is applied between the electrodes 21 and 22. It is necessary to apply a certain alternating voltage or alternating voltage. Thus, by applying an alternating voltage or an alternating voltage between the electrodes 21 and 22, it becomes possible to perform barrier discharge continuously.

  Here, when an alternating voltage is applied between the electrodes 21 and 22, the direction of the electric field applied between the electrodes 21 and 22 is reversed depending on the polarity of the applied voltage. Therefore, the direction of momentum given to electrons and ions by neutral gas molecules is also reversed by the polarity of the voltage. As a result, the flowing direction of the induced flow 25 generated along the surface of the aerodynamic noise reduction device 10, that is, the surface of the dielectric 20 is reversed depending on the polarity of the applied voltage. Further, as shown in FIG. 2, by alternately changing the polarity of the voltage, the direction in which the induced flow 25 flows changes with the change, and the induced flow 25 vibrates at a predetermined position.

  The aerodynamic noise reduction device 10 is not limited to the above-described configuration, and may include other configurations. FIG. 3 is a cross-sectional view schematically showing another embodiment of the aerodynamic noise reduction device 10 according to one embodiment of the present invention. 4 and 5 are schematic views showing the state of the induced flow velocity change. FIG. 6 is a cross-sectional view schematically showing another form of the aerodynamic noise reduction device 10 of one embodiment according to the present invention.

  As shown in FIG. 3, the aerodynamic noise reduction device 10 has an electrode 21 that is the first electrode exposed on the same plane as the surface of the dielectric 20, and the distance from the electrode 21 to the surface of the dielectric 20 is different. In addition, a voltage is applied between the electrodes 21 and 22 via the cable 23 and the electrode 22, which is the second electrode embedded in the dielectric 20 and spaced apart from the surface of the dielectric 20 in the horizontal direction. You may comprise from the power supply 24 for discharge.

  Also in this aerodynamic noise reduction device 10, when an AC voltage or an alternating voltage having a frequency equal to or lower than a predetermined value is applied between the electrodes 21 and 22 by the discharge power supply 24, the surface of the aerodynamic noise reduction device 10 is shown in FIG. That is, the induced flow 25 is generated in which the flow direction along the surface of the dielectric 20 is reversed and the flow velocity in each direction is different and vibrates. In the aerodynamic noise reduction device 10, since the electric field strength applied to the space can be increased by exposing the electrode 21, the device is driven with a lower applied voltage than when the electrode 21 is embedded in the dielectric 20. It becomes possible. Further, by adjusting the voltage value to be applied, as shown in FIG. 4 and FIG. 5, it is possible to obtain the air velocity associated with the applied voltage value. As described above, the induced flow 25 that flows in one direction on a time average basis can be generated by adjusting the applied voltage.

  Moreover, the electrode configuration in the aerodynamic noise reduction device 10 may be an electrode configuration using an ion wind phenomenon derived from a known corona discharge.

  As shown in FIG. 6, an aerodynamic noise reduction device 10 having an electrode configuration using an ionic wind phenomenon derived from this corona discharge includes an electrode 21 that is a first electrode exposed on the surface of a dielectric 20, An electrode 22, which is a second electrode that is different in distance from the surface of the electrode 21 and the surface of the dielectric 20, is spaced apart from the surface of the dielectric 20 in a horizontal direction, and is exposed on the surface of the dielectric 20; You may comprise from the power supply 24 for a discharge which applies a voltage between the electrodes 21 and 22 via the cable 23. FIG.

  Next, a phenomenon in which an induced flow is generated by the aerodynamic noise reduction device 10 will be described.

  When a voltage is applied between the electrode 21 and the electrode 22 from the discharge power supply 24 and a potential difference equals or exceeds a certain threshold value, a discharge is induced between the electrode 21 and the electrode 22. In the initial stage, the discharge is a corona discharge in which the ionization region is limited only to the vicinity of the electrode. When the shapes of the electrode 21 and the electrode 22 are not the same, corona discharge may occur only in one of the electrodes.

  When the voltage from the discharge power supply 24 is further increased, the process shifts to arc discharge that short-circuits both electrodes. In this arc discharge, the energy of the discharge is used to heat the gas. Therefore, it is preferable to apply a voltage that does not cause an arc discharge unless heat is used for airflow control.

  In a state where corona discharge is occurring, electrons or ions generated by ionization near the electrodes are accelerated by an electric field formed between the opposing electrodes. When the electrons or ions collide with the gas molecules, the momentum shifts to the gas molecules. That is, the induced current 25 can be generated near the electrodes by applying a voltage between the electrodes. The magnitude and direction of the induced current 25 can be controlled by changing the current-voltage characteristics such as the voltage, frequency, current waveform, and duty ratio applied to the electrodes.

  In the corona discharge under the atmospheric pressure as described above, it is not necessary to consider the accumulation of charges on the electrode surface. Therefore, it is preferable to apply a DC voltage between the electrodes 21 and 22, but an AC voltage is applied. Even so, the airflow induction phenomenon can be realized.

  Here, when an alternating voltage is applied between the electrodes 21 and 22, the direction of the electric field applied between the electrodes 21 and 22 is reversed depending on the polarity of the applied voltage. Therefore, the direction of momentum given to electrons and ions by neutral gas molecules is also reversed by the polarity of the voltage. As a result, the flowing direction of the induced flow 25 generated along the surface of the aerodynamic noise reduction device 10, that is, the surface of the dielectric 20 is reversed depending on the polarity of the applied voltage. Further, as shown in FIG. 2, by alternately changing the polarity of the voltage, the direction in which the induced flow 25 flows is changed along with the change, and the induced flow 25 vibrates at a predetermined position.

  As described above, according to the aerodynamic noise reduction device 10 according to the present invention, an airflow can be generated by applying a voltage between the electrodes, and this airflow is at least one of the mainstreams that generate aerodynamic noise. By acting on the flow of the part, aerodynamic noise can be reduced.

  Hereinafter, a fluid device, a moving body, a rotating device, and the like that include the above-described aerodynamic noise reduction device 10 and reduce aerodynamic noise will be described.

(Application to air outlet)
Here, a description will be given of an apparatus having the air flow outlet 50 and having the aerodynamic noise reduction device 10 disposed in the vicinity of the air flow outlet 50. FIG. 7 is a diagram schematically showing the flow downstream of the air flow outlet 50. FIG. 8 is a view showing a cross section of the air flow outlet 50 in which the aerodynamic noise reduction device 10 is provided. FIG. 9 is a perspective view of the air flow outlet 50 provided with the aerodynamic noise reduction device 10.

  As shown in FIG. 7, the noise caused by the jet 51 ejected from the air flow outlet 50 depends on the strength of the shear flow 52 around the jet (velocity gradient of the shear layer), and the shear flow 52 flows into the air outlet 50. It is known that very large aerodynamic noise is generated when there is simultaneity in the circumferential direction.

  Therefore, in order to suppress the generation of the aerodynamic noise, in the apparatus having the air flow outlet 50 according to the present invention, as shown in FIGS. A noise reduction device 10 is provided. In this device, an aerodynamic noise reduction device 10 is disposed at one place on the inner wall surface. As described above, by providing the aerodynamic noise reduction device 10, the induced flow 25 generated from the aerodynamic noise reduction device 10 can cut off the uniformity of the shear flow in the circumferential direction, and the aerodynamic noise due to the jet flow 51 is reduced. The

  In addition, the arrangement | positioning position etc. of the aerodynamic noise reduction apparatus 10 are not restricted to the above-mentioned position. Next, other arrangement positions of the aerodynamic noise reduction device 10 will be described. FIG. 10 is a view showing a cross section of the air flow outlet 50 in which the aerodynamic noise reduction device 10 is disposed at another position. FIG. 11 is a perspective view of the airflow outlet 50 in which the aerodynamic noise reduction device 10 is disposed at another position. FIG. 12 is a view showing a cross section of the air flow outlet 50 in which the aerodynamic noise reduction device 10 is disposed at another position. FIG. 13 is a perspective view of the airflow outlet 50 in which the aerodynamic noise reduction device 10 is disposed at another position.

  As shown in FIGS. 10 and 11, a plurality of aerodynamic noise reduction devices 10 may be arranged on the inner wall surface in the vicinity of the upstream side of the air flow outlet 50 at a predetermined interval along the circumferential direction. By providing the aerodynamic noise reduction device 10 in this way, the induced flow 25 generated from the aerodynamic noise reduction device 10 can more effectively cut off the uniformity of the shear flow in the circumferential direction, and the induced flow 25 Acts as a kind of turbulence promoter. As a result, the boundary layer of the airflow outlet 50 is changed to turbulent flow, the thickness of the blowout shear layer is increased, and the strength of the shear layer is reduced, so that the aerodynamic noise of the jet 51 can be further reduced. . Furthermore, since the aerodynamic noise reduction apparatus 10 is thin plate shape, the aerodynamic noise reduction apparatus 10 does not become a new aerodynamic noise source. Further, by controlling the voltage application method by the discharge power supply 24, it is possible to reduce aerodynamic noise for a wider range of blowing wind speeds. When a plurality of aerodynamic noise reduction devices 10 are provided, each aerodynamic noise reduction device 10 may be individually controlled and a different voltage may be applied to each aerodynamic noise reduction device 10.

  Also, as shown in FIGS. 12 and 13, a plurality of aerodynamic noise reduction devices 10 are arranged on the inner wall surface in the vicinity of the airflow outlet 50 by changing the distance from the airflow outlet 50 along the circumferential direction. Also good. By providing the aerodynamic noise reduction device 10 as described above, the induced flow 25 generated from the aerodynamic noise reduction device 10 can more effectively cut off the uniformity of the shear flow in the circumferential direction, and the induced flow is a kind. Acts as a turbulence promoter. As a result, the boundary layer of the airflow outlet 50 is changed to turbulent flow, the thickness of the blowout shear layer is increased, and the strength of the shear layer is reduced, so that the aerodynamic noise of the jet 51 can be further reduced. . In addition, when the several aerodynamic noise reduction apparatus 10 is arrange | positioned, you may arrange | position including the aerodynamic noise reduction apparatus 10 of a different magnitude | size.

  The above-described aerodynamic noise reduction device 10 is provided on the inner wall surface in the vicinity of the air flow outlet 50 so as to be flush with the inner wall surface without protruding toward the flow path. You may install with a predetermined blowing angle with respect to a wall surface. FIG. 14 is a perspective view of the air flow outlet 50 when the aerodynamic noise reduction device 10 is installed with a predetermined blowing angle with respect to the inner wall surface. FIG. 15 is a view showing a cross section taken along line AA of FIG.

  As shown in FIGS. 14 and 15, a recess 55 having a substantially V-shaped cross section is formed on the inner wall surface in the vicinity of the air flow outlet 50, and the inclined surface 56 on the air flow outlet 50 side of the recess 55 It is provided without protruding toward the flow path so as to be flush with the inclined surface 56. Moreover, the angle with respect to the inner wall surface of the inclined surface 56 can be set arbitrarily. By providing the aerodynamic noise reduction device 10 as described above, the uniformity of the shear flow in the circumferential direction can be cut off by the induced flow 25 generated from the aerodynamic noise reduction device 10, and the aerodynamic noise of the jet 51 can be reduced. Can do. Further, since the aerodynamic noise reduction device 10 is provided with a predetermined angle with respect to the jet flow 51, the turbulent flow in the boundary layer where the induced flow 25 from the aerodynamic noise reduction device 10 and the jet flow 51 interfere is promoted. It can be promoted more effectively, and the thickness of the blowout shear layer is increased and the strength of the shear layer is decreased. Therefore, the aerodynamic noise of the jet 51 can be further reduced.

  In addition, the shape of the airflow outlet 50 provided with the aerodynamic noise reduction device 10 is not limited to the above-described rectangular shape. FIG. 16 is a perspective view of an airflow outlet 50 having another shape in which the aerodynamic noise reduction device 10 is disposed. FIG. 17 is a perspective view of the air flow outlet 50 provided with an aerodynamic noise measuring device that measures aerodynamic noise.

  As shown in FIG. 16, the airflow outlet 50 may have a circular cross section. In this case, the aerodynamic noise reduction device 10 can be provided in the same manner as the case where the airflow outlet 50 having a rectangular cross section is provided, and FIG. 16 shows an example of the vicinity of the airflow outlet 50. 1 shows a configuration in which a plurality of aerodynamic noise reduction devices 10 are arranged on the inner wall surface at predetermined intervals along the circumferential direction. In this case as well, the same effect as when the air outlet 50 having the rectangular cross section is provided can be obtained.

  Further, as shown in FIG. 17, the aerodynamic noise reduction device 10 may be provided with an aerodynamic noise measurement device 60 that measures aerodynamic noise in the vicinity of the air flow outlet 50. The aerodynamic noise measurement device 60 mainly includes a measurement unit 61 that measures aerodynamic noise and a control unit 62. The control unit 62 is electrically connected to the measurement unit 61 and the aerodynamic noise reduction device 10 (particularly, the discharge power supply 24) via the wiring 63, and based on measurement information input from the measurement unit 61 and the measurement information. The aerodynamic noise reduction device 10 (particularly, the discharge power supply 24) is controlled. As the measurement unit 61, for example, a sound pressure sensor is used. The control unit 62 controls the discharge power supply 24 of the aerodynamic noise reduction device 10 based on the sound pressure information from the sound pressure sensor and adjusts the applied voltage. With such a configuration, it is possible to more appropriately reduce aerodynamic noise.

  The above-described aerodynamic noise reduction device 10 is arranged so that the surface of the aerodynamic noise reduction device 10 is flush with the inner wall surface of the airflow outlet 50, that is, the surface of the aerodynamic noise reduction device 10 is the inner wall surface of the airflow outlet 50. However, since the aerodynamic noise reduction device 10 can be configured to be thin as described above, it may be installed on the inner wall surface of the airflow outlet 50. Even when the aerodynamic noise reduction device 10 is installed on the inner wall surface of the air flow outlet 50, the aerodynamic noise reduction device 10 is thin and therefore does not become a source of aerodynamic noise.

(Application to centrifugal fans)
Here, a centrifugal fan 70 having a tongue 72 in the vicinity of the air flow outlet 71 and the aerodynamic noise reduction device 10 disposed in the vicinity of the tongue 72 will be described. FIG. 18 is a diagram schematically showing a cross section of the centrifugal fan 70.

  Centrifugal fan 70 is often used for home air conditioning and ventilation fans, and it is known that the shape of tongue 72 and design factors such as gap between tongue 72 and fan 73 affect aerodynamic noise ( (For example, see Noise Prevention Engineering, Motoichi Fukuda, Nikkan Kogyo Shimbun, pp. 201). In some cases, a self-excited hydrodynamic force in which the frequency determined by the number of blades and the number of rotations of the fan unit 73 and the flow in the tongue 72 is coupled is generated, resulting in a very large aerodynamic noise.

  Therefore, in order to suppress the generation of this aerodynamic noise, in the centrifugal fan 70 according to the present invention, as shown in FIG. 18, the aerodynamic noise reduction device is not projected on the inner wall surface near the tongue portion 72 without projecting to the flow path side. 10 is disposed. By providing the aerodynamic noise reduction device 10 in this way, the induced flow 25 from the aerodynamic noise reduction device 10 can disturb the main flow of the tongue 72. As a result, the self-excited chain can be broken and aerodynamic noise can be reduced. In addition, since the aerodynamic noise reduction device 10 can be configured in a thin plate shape as described above, even if it is provided in the vicinity of the tongue portion 72, the performance of the centrifugal fan 70 itself is not hindered.

  The above-described aerodynamic noise reduction device 10 is arranged so that the surface of the aerodynamic noise reduction device 10 is flush with the inner wall surface in the vicinity of the tongue 72, that is, the surface of the aerodynamic noise reduction device 10 is in the vicinity of the tongue 72. Although it is preferable that the aerodynamic noise reduction device 10 can be configured to be thin as described above, the aerodynamic noise reduction device 10 may be installed on the inner wall surface in the vicinity of the tongue 72. Even when the aerodynamic noise reduction device 10 is installed on the inner wall surface in the vicinity of the tongue portion 72, the aerodynamic noise reduction device 10 is thin and therefore does not become a generation source of aerodynamic noise. In addition, as in the case of the apparatus including the airflow outlet 50 described above, a plurality of aerodynamic noise reduction apparatuses 10 or an aerodynamic noise measurement apparatus 60 may be included.

(Application to the cavity of moving objects)
Here, the cavity 80 is provided on the outer wall surface in contact with the outside air, and the aerodynamic noise reduction device 10 is arranged on the front edge of the cavity 80 on the moving direction side (the direction of the arrow 83 in FIG. 20). The provided moving body, particularly a high-speed moving body will be described.

  FIG. 19 is a diagram showing an outline of the flow in the cavity 80. FIG. 20 is a perspective view showing a configuration of the cavity 80 provided with the aerodynamic noise reduction device 10.

  It is known that a large aerodynamic noise is generated during movement of a high-speed moving body such as a vehicle or an aircraft having a hollow portion 80 on an outer wall surface in contact with outside air, for example. As shown in FIG. 19, the aerodynamic noise in the cavity 80 is a form of typical self-excited sound in which the shear flow 81 generated from the front edge of the cavity 80 and the sound pressure reflection in the cavity resonate. Aerodynamic noise can be reduced by breaking the resonance loop of the fluctuation of the shear flow 81 and the sound pressure by generating a disturbance at the front edge of the cavity 80 (for example, thermohydrodynamics, Shoichi Fujii, Morikita Publishing Co., Ltd.) Pp. 85-86). In addition, the arrow 83 of FIG. 19 has shown the advancing direction of the moving body.

  Therefore, in order to suppress the generation of this aerodynamic noise, in the moving body according to the present invention, as shown in FIG. 20, the cavity 80 is on the moving direction side of the moving body (the arrow 83 direction side in FIG. 20). The aerodynamic noise reduction device 10 is disposed on the front edge portion 84. By providing the aerodynamic noise reduction device 10 in this way, the induced flow 25 from the aerodynamic noise reduction device 10 can disturb the shear flow. As a result, the resonance loop can be broken and aerodynamic noise can be reduced.

  The above-described aerodynamic noise reduction device 10 is arranged so that the surface of the aerodynamic noise reduction device 10 is flush with the surface of the front edge portion 84 of the cavity 80, that is, the surface of the aerodynamic noise reduction device 10 is the surface of the cavity 80. Although it is preferable that the aerodynamic noise reduction device 10 can be configured to be thin as described above, the aerodynamic noise reduction device 10 can be configured to be thin on the surface of the front edge portion 84 of the cavity 80. It may be installed. Further, even when the aerodynamic noise reduction device 10 is installed on the surface of the front edge portion 84 of the cavity portion 80, the aerodynamic noise reduction device 10 is thin and therefore does not become a generation source of aerodynamic noise. In addition, as in the case of the apparatus including the airflow outlet 50 described above, a plurality of aerodynamic noise reduction apparatuses 10 or an aerodynamic noise measurement apparatus 60 may be included.

(Application to axial fans and axial turbines)
Here, an axial fan having a guide plate for guiding the working fluid to the moving blade side, an aerodynamic noise reduction device 10 disposed near the rear edge of the guide plate, and a stationary blade for guiding the working fluid to the moving blade side are provided. The axial turbine in which the aerodynamic noise reduction device 10 is disposed in the vicinity of the trailing edge of the stationary blade will be described. In addition, an axial fan having a moving blade to which rotational force is applied by the working fluid, and an aerodynamic noise reduction device 10 disposed in the vicinity of the trailing edge of the moving blade, and a moving force to which the rotational force is applied by the working fluid. An axial flow turbine having blades and having the aerodynamic noise reduction device 10 disposed in the vicinity of the trailing edge of the blade will be described. In addition, although an axial flow turbine is illustrated and demonstrated here, the effect similar to an axial flow turbine is acquired also in an axial flow fan.

  FIG. 21 is a perspective view of the stationary blade 90 of the axial flow turbine provided with the aerodynamic noise reduction device 10. FIG. 22 is a diagram schematically illustrating a flow state in the wake of the stationary blade when the aerodynamic noise reduction device 10 is not provided. FIG. 23 is a diagram schematically illustrating a flow state in the wake of the stationary blade when the aerodynamic noise reduction device 10 is provided.

  In axial flow fans and axial flow turbines, the flow behind the guide plate and stationary blades interferes with rotating rotor blades one after another, generating large aerodynamic noise. As a method of reducing this kind of stationary blade interference sound, the gas supplied to the inside of the stationary blade by the blower for generating the jet flow is ejected, and the velocity defect of the stationary blade wake is reduced to reduce the stationary blade interference sound. (See, for example, AIAA Journal, Vol. 39, No. 3, March 2001, pp. 458-464). By this method, it is known that the interference noise is greatly reduced by the jet blowing from the trailing edge of the stationary blade.

  Therefore, in order to suppress the generation of the stationary blade interference noise by a simple method without composing the structure of the apparatus, in the axial turbine according to the present invention, as shown in FIG. The aerodynamic noise reduction device 10 is disposed in the vicinity of the rear edge portion 90 of the 90.

  Here, as shown in FIG. 22, when the aerodynamic noise reduction device 10 is not provided at the trailing edge 91 of the stationary blade 90, that is, when the induced flow 25 is not generated from the trailing edge 91 of the stationary blade 90, The velocity gradient in the wake 93 of the trailing edge 91 of the stationary blade 90 is large, and the velocity stall region 94 is increased. And it is thought that the vortex fluctuation | variation when this wake 93 interferes with the rotating rotor blade becomes large, and the generated aerodynamic noise becomes large. On the other hand, as shown in FIG. 23, when the aerodynamic noise reduction device 10 is provided at the trailing edge portion 91 of the stationary blade 90, that is, when the induced flow 25 is generated from the trailing edge portion 91 of the stationary blade 90. The velocity gradient in the wake of the trailing edge 91 of the 90 is small, and the velocity stall region 94 is small. And it is thought that the vortex fluctuation | variation when it interferes with the rotating rotor blade becomes small, and the generated aerodynamic noise becomes small.

  Moreover, in the stationary blade 90 provided with the above-described aerodynamic noise reduction device 10 according to the present invention, it is possible to generate a jet in the wake of the rear edge portion 91 of the stationary blade 90 without the need for a separate fan or the like. is there. Further, with this simple structure, the velocity stall region 94 in the wake 93 of the trailing edge 91 of the stationary blade 90 can be reduced, and the stationary blade interference noise can be reduced.

  Here, FIG. 24 shows a perspective view of a stationary blade 90 in which a plurality of aerodynamic noise reduction devices 10 are arranged. A stationary blade of an axial fan or an axial turbine often has a three-dimensional twisted shape in the radial direction. Therefore, as shown in FIG. 24, a plurality of aerodynamic noise reduction devices 10 are provided in the vicinity of the trailing edge 91 of the stationary blade 90, and the installation position thereof is appropriately selected to generate the induced flow 25 more effectively. Also good. Accordingly, the velocity stall region 94 in the wake 93 of the trailing edge 91 of the stationary blade 90 can be reduced in the radial direction and the height direction of the stationary blade 90. In addition, when the several aerodynamic noise reduction apparatus 10 is arrange | positioned, you may arrange | position including the aerodynamic noise reduction apparatus 10 of a different magnitude | size.

  Further, when a plurality of aerodynamic noise reduction devices 10 are provided, each aerodynamic noise reduction device 10 may be individually controlled and a different voltage may be applied to each aerodynamic noise reduction device 10. Accordingly, the velocity stall region 94 in the wake 93 of the trailing edge 91 of the stationary blade 90 can be further reduced in the radial direction and the height direction of the stationary blade 90.

  FIG. 25 is a cross-sectional view showing the configuration of the axial turbine including the aerodynamic noise reduction device 10. As shown in FIG. 25, the aerodynamic noise reduction device 10 may be provided with an aerodynamic noise measurement device 60 that measures the aerodynamic noise of the trailing edge 91 of the stationary blade 90. As described above, the aerodynamic noise measurement device 60 mainly includes the measurement unit 61 that measures aerodynamic noise and the control unit 62. The control unit 62 is electrically connected to the measurement unit 61 and the aerodynamic noise reduction device 10 (particularly, the discharge power supply 24) via the wiring 63, and based on measurement information input from the measurement unit 61 and the measurement information. The aerodynamic noise reduction device 10 (particularly, the discharge power supply 24) is controlled. As the measurement unit 61, for example, a sound pressure sensor is used. The control unit 62 controls the discharge power supply 24 of the aerodynamic noise reduction device 10 based on the sound pressure information from the sound pressure sensor and adjusts the applied voltage. With such a configuration, it is possible to more appropriately reduce aerodynamic noise.

  In an axial fan or an axial turbine, in order to maintain the mechanical strength of the guide plate and the stationary blade, the guide plate and the flow path formed by the guide plate and the stationary blade are disposed upstream of the guide plate and the stationary blade. In some cases, a support member that supports the stationary blade is provided. When this support member is provided, the aerodynamic noise reduction device 10 may be disposed at the rear edge portion of the support member, similarly to the guide plate and the stationary blade. Thereby, the speed stall area in the wake of the trailing edge 91 of the support member can be reduced, and the stationary blade interference noise can be reduced.

  In the above description, the application example in which the velocity stall region 94 in the wake 93 of the trailing edge 91 of the stationary blade 90 is reduced has been described. However, the present invention is not limited to this configuration. FIG. 26 is a cross-sectional view showing a configuration of an axial turbine including the aerodynamic noise reduction device 10 in the stationary blade 90 and the moving blade 100. FIG. 27 is a diagram schematically illustrating a flow state in the wake of the moving blade when the aerodynamic noise reduction device 10 is provided.

  As shown in FIG. 26, when there are a plurality of stages of the axial flow fan and the axial flow turbine, the aerodynamic noise reduction device 10 is provided in the vicinity of the rear edge portion of the rotating moving blade 100 as in the case of the stationary blade 90. May be provided. Further, as shown in FIG. 27, the aerodynamic noise reduction device 10 is provided at the trailing edge portion 101 of the moving blade 100, that is, the induced flow 25 is generated from the trailing edge portion 101 of the moving blade 100. The velocity gradient in the wake 102 of the trailing edge 101 is reduced, and the velocity stall region 103 is reduced. And the vortex fluctuation | variation at the time of interfering with the stationary blade 90 becomes small, and the generated aerodynamic noise becomes small. In addition, as shown in FIG. 26, by providing the aerodynamic noise reduction device 10 in both the stationary blade 90 and the moving blade 100, the effect of reducing interference noise can be improved.

  Note that the aerodynamic noise reduction device 10 described above is such that the surface of the aerodynamic noise reduction device 10 is flush with the surfaces of the stationary blade 90, the moving blade 100, and the rear edge of the support member, that is, the aerodynamic noise reduction device 10. However, the aerodynamic noise reduction device 10 can be configured to be thin as described above. However, as described above, the aerodynamic noise reduction device 10 can be configured to be thin. Therefore, it may be installed on the surface of the trailing edge of the stationary blade 90, the moving blade 100, and the support member. Further, even when the aerodynamic noise reduction device 10 is installed on the surfaces of the stationary blade 90, the moving blade 100, and the rear edge portion of the support member, the aerodynamic noise reduction device 10 is thin, Never become.

(Application to rotor blades)
Here, a rotating device and a moving body that have rotating blades and in which the aerodynamic noise reduction device 10 is disposed in the vicinity of the rear edge of the rotating blade will be described.

  FIG. 28 is a perspective view of the rotor blade 110 provided with the aerodynamic noise reduction device 10. FIG. 29 is a perspective view of a rotor blade 110 provided with an aerodynamic noise measuring device that measures aerodynamic noise.

  In a rotor blade such as a helicopter or a windmill, a large aerodynamic noise is generated when the rotating blade is subjected to lift fluctuation. Blade force variation occurs because the wake of the rotor blade located in front of the rotation direction interferes with the next blade.

  Therefore, in order to suppress the generation of this aerodynamic noise, the aerodynamic noise reduction device 10 is disposed at the rear edge portion 111 of the rotary blade 110 in the rotating device or moving body according to the present invention as shown in FIG. ing. By providing the aerodynamic noise reduction device 10 and generating the induced flow 25 from the aerodynamic noise reduction device 10 in this way, the velocity deficit in the wake of the trailing edge 111 of the rotor blade 110 can be reduced. Therefore, it is possible to weaken the shear vortex generated in the velocity deficit region in the wake of the trailing edge 111 of the rotor blade 110, and to suppress the lift fluctuation that occurs when the rotor blade 110 interferes with the next rotor blade 110. Thereby, aerodynamic noise can be reduced. The hydrodynamic mechanism for weakening the interference sound between the wake and the rotor blade 110 is the same as the hydrodynamic mechanism in the case of the axial fan and the axial turbine described above.

  Further, as shown in FIG. 29, the aerodynamic noise reduction device 10 may be provided with an aerodynamic noise measurement device 60 that measures the aerodynamic noise of the trailing edge 111 of the rotor blade 110. As described above, the aerodynamic noise measurement device 60 mainly includes the measurement unit 61 that measures aerodynamic noise and the control unit 62. The control unit 62 is electrically connected to the measurement unit 61 and the aerodynamic noise reduction device 10 (particularly, the discharge power supply 24) via the wiring 63, and based on measurement information input from the measurement unit 61 and the measurement information. The aerodynamic noise reduction device 10 (particularly, the discharge power supply 24) is controlled. As the measurement unit 61, for example, a sound pressure sensor is used. The control unit 62 controls the discharge power supply 24 of the aerodynamic noise reduction device 10 based on the sound pressure information from the sound pressure sensor and adjusts the applied voltage. With such a configuration, it is possible to more appropriately reduce aerodynamic noise.

  Note that the aerodynamic noise reduction device 10 described above is such that the surface of the aerodynamic noise reduction device 10 is flush with the surface of the trailing edge 111 of the rotor blade 110, that is, the surface of the aerodynamic noise reduction device 10 is the rotor blade. 110 is preferably arranged so as not to protrude from the surface of the trailing edge 111 of the 110, but as described above, the aerodynamic noise reduction device 10 can be configured to be thin. It may be installed on top. Further, even when the aerodynamic noise reduction device 10 is installed on the surface of the trailing edge 111 of the rotor blade 110, the aerodynamic noise reduction device 10 is thin and therefore does not become a generation source of aerodynamic noise.

  Although the present invention has been specifically described above with reference to the embodiments, the present invention is not limited to these embodiments, and various modifications can be made without departing from the scope of the invention.

1 is a cross-sectional view schematically showing an aerodynamic noise reduction device according to an embodiment of the present invention. The schematic diagram which showed the condition of the speed change of an induced flow. Sectional drawing which showed typically the other form of the aerodynamic noise reduction apparatus of one Embodiment which concerns on this invention. The schematic diagram which showed the condition of the speed change of an induced flow. The schematic diagram which showed the condition of the speed change of an induced flow. Sectional drawing which showed typically the other form of the aerodynamic noise reduction apparatus of one Embodiment which concerns on this invention. The figure which showed typically the flow downstream of an airflow outlet. The figure which shows the cross section of the air flow outlet which arrange | positioned the aerodynamic noise reduction apparatus. The perspective view of the air flow outlet which arrange | positioned the aerodynamic noise reduction apparatus. The figure which shows the cross section of the airflow outlet which arrange | positioned the aerodynamic noise reduction apparatus in the other position. The perspective view of the airflow outlet which has arrange | positioned the aerodynamic noise reduction apparatus in another position. The figure which shows the cross section of the airflow outlet which arrange | positioned the aerodynamic noise reduction apparatus in the other position. The perspective view of the airflow outlet which has arrange | positioned the aerodynamic noise reduction apparatus in another position. The perspective view of the airflow blowing outlet at the time of installing an aerodynamic noise reduction apparatus with a predetermined blowing angle with respect to an inner wall surface. The figure which shows the AA cross section of FIG. The perspective view of the airflow blower outlet of the other shape which arrange | positioned the aerodynamic noise reduction apparatus. The perspective view of the air flow outlet provided with the aerodynamic noise measuring device which measures aerodynamic noise. The figure which showed the cross section of the centrifugal fan typically. The figure which shows the outline of the flow in a cavity part. The perspective view which shows the structure of the cavity part provided with the aerodynamic noise reduction apparatus. The perspective view of the stationary blade of an axial flow turbine provided with the aerodynamic noise reduction apparatus. The figure which showed typically the mode of the flow in the wake of a stationary blade in case the aerodynamic noise reduction apparatus is not provided. The figure which showed typically the mode of the flow in the wake of a stationary blade at the time of providing an aerodynamic noise reduction apparatus. The perspective view of the stationary blade in which the several aerodynamic noise reduction apparatus was arrange | positioned. Sectional drawing which shows the structure of the axial flow turbine provided with the aerodynamic noise reduction apparatus. Sectional drawing which shows the structure of the axial flow turbine provided with the aerodynamic noise reduction apparatus in the stationary blade and the moving blade. The figure which showed typically the mode of the flow in a moving blade wake in the case of providing an aerodynamic noise reduction apparatus. The perspective view of the rotary blade provided with the aerodynamic noise reduction apparatus. The perspective view of a rotary blade provided with the aerodynamic noise measuring device which measures aerodynamic noise.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Aerodynamic noise reduction apparatus, 20 ... Dielectric, 21,22 ... Electrode, 23 ... Cable, 24 ... Electric power source for discharge, 25 ... Airflow.

Claims (12)

A first electrode;
A second electrode spaced apart from the first electrode;
A voltage application mechanism capable of applying an alternating voltage between the first electrode and the second electrode;
Reducing the aerodynamic noise by generating an air flow by discharge between the first electrode and the second electrode, causing the air flow to act on at least a part of a main flow that is a generation source of aerodynamic noise; A characteristic aerodynamic noise reduction device. A measuring means for measuring aerodynamic noise;
The control means for controlling a voltage applied between the first electrode and the second electrode based on information from the aerodynamic noise measurement device, further comprising: Aerodynamic noise reduction device. The aerodynamic noise reduction device according to claim 1 , wherein the voltage application mechanism performs intermittent voltage application and / or voltage application while adjusting a voltage value . A fluid device comprising the aerodynamic noise reduction device according to any one of claims 1 to 3. 5. The fluid device according to claim 4, wherein the fluid device is a device having an air flow outlet, and the aerodynamic noise reduction device is disposed in the vicinity of the air flow outlet . 5. The fluid device according to claim 4, wherein the fluid device is a centrifugal fan having a tongue portion in the vicinity of the air flow outlet, and the aerodynamic noise reduction device is disposed in the vicinity of the tongue portion. . The fluid device is one of an axial flow fan having a guide plate for guiding the working fluid to the moving blade side and an axial flow turbine having a stationary blade for guiding the working fluid to the moving blade side, the guide plate or after the stationary blade The fluid device according to claim 4, wherein the aerodynamic noise reduction device is disposed in the vicinity of the edge . The axial flow fan further includes a support member provided to maintain the mechanical strength of the guide plate or the stationary blade, and the aerodynamic noise reduction device is disposed in the vicinity of the rear edge of the support member. The fluid device according to claim 7 , wherein the fluid device is provided. The fluid device is one of an axial flow fan and an axial flow turbine having a moving blade to which a rotational force is applied by a working fluid, and the aerodynamic noise reduction device is arranged in the vicinity of a rear edge portion of the moving blade. The fluid device according to claim 4 , wherein the fluid device is provided. 4. The aerodynamic noise reduction according to claim 1, wherein the moving body has a hollow portion on an outer wall surface that is in contact with outside air, and a front edge portion of the hollow portion on a traveling direction side of the moving body. A moving body provided with a device. A moving body having a rotating blade, wherein the aerodynamic noise reduction device according to any one of claims 1 to 3 is disposed in the vicinity of a rear edge portion of the rotating blade . A rotary device having a rotary blade, wherein the aerodynamic noise reduction device according to any one of claims 1 to 3 is disposed in the vicinity of a rear edge portion of the rotary blade.

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